in January, frustrating that company’s hopes to get a copy on the market by 2017.

AbbVie in October said Humira would be safe for years to come, projecting sales of more than $18 billion in 2020. Competition may arrive in Europe as soon as 2018, AbbVie has said, but shouldn’t be a factor in the U.S. until much later. The company has 70 plus U.S. patents on the drug that don’t start expiring until 2022. It also suggested legal action around any biosimilar competitor could take up to five years to resolve.

That guidance boosted analyst expectations for Humira sales, as did the Amgen decision a few months later. Before Tuesday’s decision, Wall Street consensus had the drug’s sales peaking in 2018 at $17.8 billion.

Competitors now have a clear way in. The patent that could be invalidated by Coherus is a “cornerstone” of the Humira patent estate, according to Barclays analyst Geoffrey Meacham. Adding to the risks to AbbVie, the PTAB will decide whether to review Coherus challenges on two other Humira patents by June 15.

If the first patent falls, then so might others, which could lead to faster U.S. competition for Humira. That would put a lot more pressure on the company’s pipeline of other drugs.

and big investments in cancer medicines. AbbVie has spent heavily for some promising treatments, but making up for Humira’s eventual decline is a lot to ask.

This column does not necessarily reflect the opinion of Bloomberg LP and its owners.

To contact the author of this story: Max Nisen inNew York at mnisenbloomberg.net To contact the editor responsible for this story: Mark Gongloff at mgongloff1bloomberg.net